1. Field of the Invention
The present invention relates to a field winding type rotary electric machine having an armature winding and a field winding, the field winding type rotary electric machine being mounted mainly on a vehicle and provided with a control device.
2. Description of the Related Art
Generally, a vehicular rotary electric machine is mounted on an engine room; and therefore, the operating temperature of the vehicular rotary electric machine reaches extremely high temperature. Furthermore, the internal temperature of the vehicular rotary electric machine reaches higher temperature due to the heat generated when the vehicular rotary electric machine performs operation such as power generation and driving. Accordingly, when the temperature of the vehicular rotary electric machine excessively rises due to long periods of continuous operation and the like, it is likely to generate failure in the vehicular rotary electric machine due to damage of internal components.
Therefore, in an output control method and an output control device of a conventional vehicular AC (alternating current) generator, as means for preventing failure of the vehicular AC generator due to a temperature rise, there is proposed a method in which, when the temperature of the AC generator or ambient temperature thereof is measured and it is detected that the measured temperature exceeds a preliminarily set abnormal temperature value, AC generator output current is limited to reduce thermal burden of the control device (for example, see Patent Document 1). More specifically, there is disclosed a technique in which a PWM (pulse width modulation) control comparator 910 compares a first or second level voltage outputted by a comparator 902 based on a temperature proportional voltage generate by an amplifier 901 with a triangular wave voltage generated by a triangular wave generator to generate a pulse width modulation wave signal; and in a temperature range exceeding a predetermined temperature, intermittent control of a power transistor 305 is performed by the pulse width modulation wave signal and accordingly a field current flowing through a field coil 102A is limited. This makes it possible to prevent defects caused by AC generation or thermal runaway of its control device.